The present invention relates to wheelchairs, and particularly to wheelchairs capable of moving various movable members such as the seat frame and back fame.
Wheelchairs often have a fixed seat consisting of a seating surface and a back frame. The seating surface is usually either horizontal or slightly tilted back, with the front edge of the seating surface slightly higher than the rear edge of that surface. If the wheelchair user sits in the same position in a wheelchair for a long period of time, pressure is continuously applied to the tissue on the portion of the user""s body (buttocks, legs, and/or back) that is bearing the user""s weight in that position. Blood circulation to that tissue will be reduced, and ulcers or other problems can result.
To avoid these problems, it is necessary for people sitting in wheelchairs to shift their body weight from time to time. This is often accomplished by tilting the seat portion of the wheelchair backwards so that the user""s weight is shifted away from the pressure points on the user""s body. Also, the user""s weight can be shifted by reclining the back frame.
It would be advantageous if there could be developed a wheelchair having improved methods for reclining and/or tilting. Further, it would be advantageous if there could be developed improved methods and apparatus for controlling the movement of various movable wheelchair elements such as back frames, seat frames, head rests, arm rests, leg rests and foot rests.
The above objects as well as other objects not specifically enumerated are achieved by a method of operating a wheelchair having tilt and recline functions, the wheelchair including a seat frame, a tilt actuator for tilting the seat frame, a back frame, a recline actuator for reclining the back frame. A sensor for determining the angle of recline is provided. A controller for controlling the tilt actuator and recline actuator is also provided. The controller is provided with a plurality of preprogrammed sequences for moving the seat frame and the back frame during an unrecline procedure. The sequences include tilting the seat frame as an initial part of the unrecline sequence, wherein the sequences are a function of the initial angle of recline at the initiation of the recline sequence. An initial angle of recline at the initiation of a recline sequence is determined, and the back frame is unreclined according to one of the preprogrammed sequences in response to the determined initial angle of recline.
According to this invention there is also provided a method of operating a wheelchair having a recline function, the wheelchair including a back frame, a recline actuator for reclining the back frame, a recline sensor for determining the angle of recline, and a controller for controlling the recline actuator. The controller has a memory device. A plurality of angles of recline of the back frame are selected, and data corresponding to the selected angles of recline is stored in the memory device. An input device for a wheelchair operator, and connected to the controller, is provided. The input device has a plurality of switches operatively connected to the controller. The controller is programmed to associate each of the selected angles of recline with one of the switches so that activating each switch causes the controller to access the stored data and return the back frame to the selected angle of recline associated with the switch.
According to this invention there is also provided a method of operating a wheelchair having tilt and recline functions, the wheelchair including a seat frame, a tilt actuator for tilting the seat frame, a back frame, a recline actuator for reclining the back frame, a sensor for determining the angle of recline, and a controller for controlling the tilt actuator and recline actuator. The controller is programmed with a preprogrammed unrecline sequence for moving the seat frame and the back frame during an unrecline procedure. The unrecline sequence includes tilting the seat frame as an initial part of the unrecline sequence. The controller is programmed with a threshold recline angle, above which the unrecline procedure follows the preprogrammed unrecline sequence, and below which the unrecline procedure involves unreclining the back frame without tilting the seat frame. An initial angle of recline at the initiation of unrecline sequences during operation of the wheelchair is determined. The initial angle of recline is compared with the threshold angle. The back frame is unreclined in response to the comparison of the initiation angle with the threshold angle.
According to this invention there is also provided apparatus as disclosed herein to carry out the methods of the invention as described above and elsewhere in the specification and drawings, as well as wheelchairs as described herein.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.